Built during the 10th -11th Century, Prasat Don Tuan near Ban Phume Sarol is actually 350 meters onto the Cambodia side of the distinct watershed border ridge. The only road access, however, is from Thailand. Legend tells that in the past a lady known as Nang Nom Yai or Nieng Non dor (in Khmer), stopped to rest here on her way to visit a king.
According to Google Map there are two adjacent temple ruins, the one noted as Prasat Don Tual (or Tuan), relates to the narative while Prasat Doun Tea is clearly the one in the photographs. Clarification is clearly needed due to the lack of onsite information.

Source: site visit